Radiolabelled Mgl Pet Ligands

This application is a Continuation of application Ser. No. 18/526,575 filed on Dec. 1, 2023, which is a Continuation of application Ser. No. 17/036,919 filed on Sep. 29, 2020, now U.S. Pat. No. 11,839,663, which claims priority from Provisional Application No. 62/907,852 filed on Sep. 30, 2029, the entire disclosures of which are hereby incorporated in their entirety.

The present invention relates to a novel, selective, compound having monoacylglycerol lipase (MGL) affinity, and in one embodiment containing a positron-emitting radioligand to enable positron-emission tomography (PET); a pharmaceutical composition comprising the compound, using the compound to assess MGL receptor expression, distribution and enzyme occupancy, and diagnosis of diseases, disorders or conditions associated with MGL receptor activity in subjects, in particular humans.

Cannabis Sativa and analogs of Δ-tetrahydrocannabinol have been used since the days of folk medicine for therapeutic purposes. The endocannabinoid system consists of two G-protein coupled receptors, cannabinoid receptor type 1 (CB1) (Matsuda et al.,1990, 346, 561-4) and cannabinoid receptor type 2 (CB2) (Munro et al.,1993, 365, 61-5). CB1 receptor is one of the most abundant G-protein coupled receptor expressed in the brain (Herkenam et al.,1990, 87 (5), 1932-1936). CB1 is also expressed peripherally in the liver, gastrointestinal tract, pancreas, adipose tissue and skeletal muscles (Di Marzo et al.,2007, 18, 129-140). CB2 is predominantly expressed in immune cells such as monocytes (Pacher et al.,2008, 294, H1133-H1134) and under certain conditions (inflammation) in the brain ((Benito et al.,2008, 153, 277-285) and in skeletal (Cavuoto et al.,2007, 364, 105-110) and cardiac muscles (Hajrasouliha et al.,2008, 579, 246-252).

In 1992, N-arachidonoylethanolamine (AEA or anandamide) was found to be an endogenous ligand for cannabinoid receptors (Devane et al.,1992, 258, 1946-9). Subsequently, 2-arachidonoylglycerol (2-AG) was also identified as an additional endogenous ligand for the cannabinoid receptors (Mechoulam et al.,1995, 50, 83-90; Sugiura et al.,1995, 215, 89-97). Concentrations of 2-AG were reported to be at least 100 times higher than these of anandamide in the rat brain (Buczynski and Parsons,2010, 160 (3), 423-42). Therefore 2-AG may play more essential physiological roles than anandamide in the brain endocannabinoid system (Sugiura et al.2002 February-March, 66(2-3):173-92). The endocannabinoid 2-AG is a full agonist for CB1 and CB2 receptors, while anandamide is a partial agonist for both receptors (Suguira et al.,2006, 45(5):405-46). Unlike many classical neurotransmitters, endocannabinoids signal through a retrograde mechanism. They are synthesized on demand in postsynaptic neurons and then rapidly degraded following binding to presynaptic cannabinoid receptors (Ahn et al.,2008, 108(5):1687-707). Monoacylglycerol lipase (MGLL, also known as MAG lipase and MGL) is the serine hydrolase responsible for the degradation of 2-AG into arachidonic acid and glycerol in the central nervous system (Mechoulam et al.,1995, 50, 83-90; Sugiura et al.,1995, 215, 89-97; Long et al.,2009 January;5(1):37-44;), Schlosburg et al,2010 September;13(9):1113-9) and peripheral tissues (Long et al.,2009 Jul. 31;16(7):744-53). Anandamide is hydrolyzed by fatty acid amide hydrolase (FAAH) (Piomelli,2003, 4, 873-884). MGL exists in both soluble and membrane bound forms (Dinh et al.,2002, Aug. 6;99(16):10819-24). In the brain MGL is located in presynaptic neurons (Straiker et al.,2009 December;76(6):1220-7) and astrocytes (Walter et al.,2004 Sep. 15;24(37):8068-74) within regions associated with high CB1 receptor density. Compared to wild-type controls, genetic ablation of MGL expression produces 10-fold increase in brain 2-AG levels without affecting anandamide concentration (Schlosburg et al.,2010 September;13(9):1113-9).

Thus, MGL modulation offers an interesting strategy for potentiating the cannabinoid system. The primary advantage of this approach is that only brain regions where endocannabinoids are actively produced will be modulated, potentially minimizing the side effects associated with exogenous CB1 agonists. Pharmacological inactivation of MGL by covalent inhibitors in animals increase 2-AG content in brain and peripheral tissues and has been found to produce antinociceptive, anxiolytic and anti-inflammatory effects that are dependent on CB1 and/or CB2 receptors (Long et al.,2009 January, 5(1):37-44; Ghosh et al.,2013 Mar. 19, 92(8-9):498-505; Bedse et al.,2017 Oct. 1, 82(7):488-499; Bernal-Chico et al.,2015 January, 63(1):163-76; Patel et al.2017 May, 76(Pt A):56-66; Betse et al.,2018 Apr. 26, 8(1):92). In addition to the role of MGL in terminating 2-AG signaling, MGL modulation, including MGL inhibition also promotes CB1/2-independent effects on neuroinflammation (Nomura et al.,2011 Nov. 11;334(6057):809-13). MGL modulation, including MGL inhibition leads to reduction in proinflammatory prostanoid signaling in animal models of traumatic brain injury (Katz et al.,2015 Mar. 1;32(5):297-306; Zhang et al.,2015 Mar. 31;35(4):706), neurodegeneration including Alzheimer's disease (Piro et al., Cell Rep., 2012 Jun. 28, 1(6):617-23; Wenzel et al., Life Sci., 2018 Aug. 15, 207:314-322; Chen et al., Cell Rep., 2012 Nov. 29, 2(5):1329-39), Parkinson's disease (Nomura et al., Science, 2011 Nov. 11, 334(6057), 809-13; Pasquarelli et al., Neurochem Int., 2017 November, 110:14-24), amyotrophic lateral sclerosis (Pasquarelli et al., Neuropharmacology, 2017 Sep. 15, 124:157-169), multiple sclerosis (Hernadez-Torres et al., Angew Chem Int Ed Engl., 2014 Dec. 8, 53(50):13765-70; Bernal-Chico et al., Glia., 2015 January, 63(1):163-76), Huntington's disease (Covey et al., Neuropsychopharmacology, 2018, 43, 2056-2063), Tourette syndrome and status epilepticus (Terrone et al.,2018 January, 59(1), 79-91; von Ruden et al.,2015 May;77:238-45).

Therefore, by potentiating the cannabinoid system and attenuating proinflammatory cascades, MGL modulation, including MGL inhibition offers a compelling therapeutic approach for the treatment of a vast array of complex diseases. Importantly, MGL modulation, including MGL inhibition in animals does not produces the full spectrum of neurobehavioral effects observed with Δ-tetrahydrocannabinol and other CB1 agonists (Tuo et al.,2017 Jan. 12, 60(1), 4-46; Mulvihill et al.,2013 Mar. 19, 92(8-9), 492-7).

Endocannabinoid hypoactivity is a risk factor for the treatment of depression, anxiety and post-traumatic stress disorders. Millennia of human use of cannabis sativa, and a brief period in which humans were treated with the endocannabinoid antagonist, rimonabant, provide support for that hypothesis. 2-AG levels are decreased in individuals with major depression (Hill et al.,2008 March; 41(2): 48-53; Hill et al.,2009 September; 34(8): 1257-1262.). Low circulating 2-AG levels predict rates of depression (Hauer et al.,2012, 23(5-6):681-90). Reduced circulating 2-AG has been found in patient with post-traumatic stress disorder (PTSD) (Hill et al.,2013, 38 (12), 2952-2961). Healthy volunteers exposed to chronic stressors exhibited progressively diminished circulating 2-AG levels which correlated with the onset of reductions in measures of positive emotions (Yi et al.,-2016, 67 (3), 92-97). The CB1 receptor inverse agonist/antagonist Rimonabant has been withdrawn from the market due to the high incidence of severe depression and suicidal ideation (Christensen et al.,2007, 370, 1706-1713). Therefore, MGL modulators are potentially useful for the treatment of mood disorders, anxiety and PTSD.

Cannabinoid receptor agonists are clinically used to treat pain, spasticity, emesis and anorexia (Di Marzo, et al.,2006, 57:553-74; Ligresti et al.,2009 June;13(3):321-31). Therefore, MGL modulators, including MGL inhibitors are also potentially useful for these indications. MGL exerts CB1-dependant antinociceptive effects in animal models of noxious chemical, inflammatory, thermal and neuropathic pain (Guindon et al.,2011 August;163(7):1464-78; Kinsey et al.,2009 September;330(3):902-10; Long et al.,2009 January;5(1):37-44). MGL blockade reduces mechanical and acetone induced cold allodynia in mice subjected to chronic constriction injury of the sciatic nerve (Kinsey et al.,2009, September;330(3):902-10). MGL inhibition produces opiate-sparing events with diminished tolerance, constipation, and cannabimimetic side effects (Wilkerson et al.,2016 April;357(1):145-56). MGL blockade is protective in model of inflammatory bowel disease (Alhouayek et al.,2011 August;25(8):2711-21). MGL inhibition also reverse Paclitaxel-induced nociceptive behavior and proinflammatory markers in a mouse model of chemotherapy-induced neuropathy (Curry et al.,2018 July;366(1):169-18).

Inhibition of 2-AG hydrolysis exerts anti-proliferative activity and reduction in prostate cancer cell invasiveness (Nithipatikom et al.,2004 Dec. 15, 64(24):8826-30; Nithipatikom et al.,2005 Jul. 15,332(4):1028-33; Nithipatikom et al.,2011, February, 94(1-2):34-43). MGL is upregulated in aggressive human cancer cells and primary tumors where it has a unique role of providing lipolytic sources of free fatty acids for synthesis of oncogenic signaling lipids that promote cancer aggressiveness. Thus, beyond the physiological roles of MGL in mediated endocannabinoid signaling, MGL in cancer plays a distinct role in modulating the fatty acid precursor pools for synthesis of protumorigenic signaling lipids in malignant human cancer cells.

MGL blockade shows anti-emetic and anti-nausea effects in a lithium chloride model of vomiting in shrews (Sticht et al.,2012 April, 165(8):2425-35).

MGL modulators, including MGL inhibitors may have utility in modulating drug dependence of opiates. MGL blockade reduce the intensity of naloxone-precipitated morphine withdrawal symptoms in mice. MGL blockade also attenuated spontaneous withdrawal signs in morphine-dependent mice (Ramesh et al.,2011 October, 339(1):173-85).

MGL modulators are also potentially useful for the treatment of eye conditions, including but not limited to, glaucoma and disease states arising from elevated intraocular pressure (Miller et al.,2018, 11, 50).

Positron Emission Tomography (PET) is a non-invasive imaging technique that offers the highest spatial and temporal resolution of all nuclear imaging techniques and has the added advantage that it can allow for true quantification of tracer concentrations in tissues. It uses positron emitting radionuclides such as, for example,O,N,C andF for detection. There is a need to provide positron emission tomography radiotracers for evaluation of MGL's expression, distribution and occupancy by its inhibitors. The imaging agent would play a critical role in such a research and in the development of therapeutic candidates targeting MGL.

The present invention relates to a compound having the Formula (I)

or a pharmaceutically acceptable salt, or a solvate thereof. In one embodiment, the compound of Formula (I) has at least one atom that is radioactive.

In a particular embodiment, the compound of Formula (I) is a compound of Formula (IA),

or a pharmaceutically acceptable salt or a solvate thereof.

The invention also relates to a pharmaceutical composition comprising a compound of Formula (I) (as well as a compound of Formula (IA)) or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier or diluent. In a particular embodiment, said pharmaceutical composition is particularly suitable for diagnosis and may be referred to therefore as a diagnostic pharmaceutical composition. In particular, said pharmaceutical composition is a sterile solution. Thus, illustrative of the invention is a sterile solution comprising a compound of Formula (I) (as well as a compound of Formula (IA)) described herein.

The invention further relates to the use of a compound of Formula (I) (as well as a compound of Formula (IA)) as an imaging agent. Therefore, exemplifying the invention is a use of a compound of Formula (I) (as well as a compound of Formula (IA)) as described herein, for, or a method of, imaging a tissue, cells or a mammal, in vitro or in vivo. In particular, the invention relates to a compound of Formula (I) (as well as a compound of Formula (IA)) as described herein, for use as a contrast agent for imaging a tissue, cells or a mammal, in vitro, ex vivo, or in vivo. The invention further relates to a composition comprising a compound of Formula (I) (as well as a compound of Formula (IA)) for use as a contrast agent for imaging a tissue, cells or a mammal, in vitro, ex vivo, or in vivo.

The invention also relates to a method for imaging a tissue, cells or a mammal, comprising contacting with or providing or administering a detectable amount of a labelled compound of Formula (I) (as well as a compound of Formula (IA)) as described herein to a tissue, cells or a mammal, and detecting the compound of Formula (I) (as well as a compound of Formula (IA)).

Further exemplifying the invention is a method of imaging a tissue, cells or a mammal, comprising contacting with or providing or administering to a tissue, cells or a mammal, a compound of Formula (I) (as well as a compound of Formula (IA)) as described herein, and imaging the tissue, cells or mammal with a positron-emission tomography imaging system.

The present invention is directed to compounds of Formula (I) (as well as a compound of Formula (IA)) as defined herein before, and pharmaceutically acceptable salts thereof. The present invention is also directed to the precursor compound of Formula (IB), used in the synthesis of compounds of Formula (IA).

In one embodiment of the present invention, is a compound of Formula (I):

In one embodiment of the present invention, is a compound of Formula (IA):

In a further embodiment, the compound of Formula (I) as previously described is selected from the group consisting of:

As already mentioned, the compounds of Formula (I) (as well as a compound of Formula (IA)) and compositions comprising the compounds of Formula (I) (as well as a compound of Formula (IA)) can be used for imaging a tissue, cells or a host, in vitro or in vivo. In particular, the invention relates to a method of imaging or quantifying MGL's expression, distribution and occupancy by its inhibitors in tissue, cells or a host in vitro or in vivo. The cells and tissues are preferably central nervous system cells and tissues in which the MGL enzyme are abundant.

When the method is performed in vivo, the host is a mammal. In such particular cases, the compound of Formula (IA) is administered intravenously, for example, by injection with a syringe or by means of a peripheral intravenous line, such as a short catheter.

When the host is a human, the compound of Formula (IA) or a sterile solution comprising a compound of Formula (IA), may in particular be administered by intravenous administration in the arm, into any identifiable vein, in particular in the back of the hand, or in the median cubital vein at the elbow.

Thus, in a particular embodiment, the invention relates to a method of imaging a tissue or cells in a mammal, comprising the intravenous administration of a compound of Formula (IA), as defined herein, or a composition comprising a compound of Formula (IA) to the mammal, and imaging the tissue or cells with a positron-emission tomography imaging system.

Thus, in a further particular embodiment, the invention relates to a method of imaging a tissue or cells in a human, comprising the intravenous administration of a compound of Formula (IA), as defined herein, or a sterile formulation comprising a compound of Formula (IA) to the human, and imaging the tissue or cells with a positron-emission tomography imaging system.

In a further embodiment, the invention relates to a method of imaging or quantifying MGL's expression in a mammal, comprising the intravenous administration of a compound of Formula (IA), or a composition comprising a compound of Formula (IA) to the mammal, and imaging with a positron-emission tomography imaging system.

In another embodiment, the invention relates to the use of a compound of Formula (IA) for imaging a tissue, cells or a host, in vitro or in vivo, or the invention relates to a compound of Formula (IA), for use in imaging a tissue, cells or a host in vitro or in vivo, using positron-emission tomography.

As used herein, the term “composition” is intended to encompass a product comprising the specified ingredients in the specified amounts, as well as any product which results, directly or indirectly, from combinations of the specified ingredients in the specified amounts.

Addition salts of the compounds according to Formula (I) and of the compounds of Formula (IA) can also form stereoisomeric forms and are also intended to be encompassed within the scope of this invention.

The term “an MGL inhibitor containing a positron emission tomography (“PET”) tracer radionuclide” means that one or more atoms of the MGL inhibitor are replaced PET tracer radionuclide. In some embodiments, a fluorine atom of the MGL inhibitor is replaced byF. In some embodiments, a carbon atom of the MGL inhibitor is replaced byC. In some embodiments a nitrogen atom of the MGL inhibitor is replaced byN. In some embodiments a nitrogen atom of the MGL inhibitor is replaced byO.

A “pharmaceutically acceptable salt” is intended to mean a salt of an acid or base of a compound represented by Formula (I) (as well as Formula (IA)) that is non-toxic, biologically tolerable, or otherwise biologically suitable for administration to the subject. See, generally, S. M. Berge, et al., “Pharmaceutical Salts”, J. Pharm. Sci., 1977, 66:1-19, andStahl and Wermuth, Eds., Wiley-VCH and VHCA, Zurich, 2002. Preferred pharmaceutically acceptable salts are those that are pharmacologically effective and suitable for contact with the tissues of patients without undue toxicity, irritation, or allergic response.

A compound of Formula (I) (as well as Formula (IA)) may possess a sufficiently acidic group, a sufficiently basic group, or both types of functional groups, and accordingly react with a number of inorganic or organic bases, and inorganic and organic acids, to form a pharmaceutically acceptable salt.

Examples of pharmaceutically acceptable salts include sulfates, pyrosulfates, bisulfates, sulfites, bisulfites, phosphates, monohydrogen-phosphates, dihydrogenphosphates, metaphosphates, pyrophosphates, chlorides, bromides, iodides, acetates, propionates, decanoates, caprylates, acrylates, formates, isobutyrates, caproates, heptanoates, propiolates, oxalates, malonates, succinates, suberates, sebacates, fumarates, maleates, butyne-1,4-dioates, hexyne-1,6-dioates, benzoates, chlorobenzoates, methylbenzoates, dinitrobenzoates, hydroxybenzoates, methoxybenzoates, phthalates, sulfonates, xylenesulfonates, phenylacetates, phenylpropionates, phenylbutyrates, citrates, lactates, γ-hydroxybutyrates, glycolates, tartrates, methane-sulfonates, propanesulfonates, naphthalene-1-sulfonates, naphthalene-2-sulfonates, and mandelates.

Compounds of Formula (I) (as well as Formula (IA)) may contain at least one nitrogen of basic character, so desired pharmaceutically acceptable salts may be prepared by any suitable method available in the art, for example, treatment of the free base with an inorganic acid, such as hydrochloric acid, hydrobromic acid, sulfuric acid, sulfamic acid, nitric acid, boric acid, phosphoric acid, and the like, or with an organic acid, such as acetic acid, phenylacetic acid, propionic acid, stearic acid, lactic acid, ascorbic acid, maleic acid, hydroxymaleic acid, isethionic acid, succinic acid, valeric acid, fumaric acid, malonic acid, pyruvic acid, oxalic acid, glycolic acid, salicylic acid, oleic acid, palmitic acid, lauric acid, a pyranosidyl acid, such as glucuronic acid or galacturonic acid, an alpha-hydroxy acid, such as mandelic acid, citric acid, or tartaric acid, an amino acid, such as aspartic acid or glutamic acid, an aromatic acid, such as benzoic acid, 2-acetoxybenzoic acid, naphthoic acid, or cinnamic acid, a sulfonic acid, such as laurylsulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, any compatible mixture of acids such as those given as examples herein, and any other acid and mixture thereof that are regarded as equivalents.

Compounds of Formula (I) (as well as Formula (IA)) may contain a carboxylic acid moiety, a desired pharmaceutically acceptable salt may be prepared by any suitable method, for example, treatment of the free acid with an inorganic or organic base, such as an amine (primary, secondary or tertiary), an alkali metal hydroxide, alkaline earth metal hydroxide, any compatible mixture of bases such as those given as examples herein, and any other base and mixture thereof that are regarded as equivalents or acceptable substitutes in light of the ordinary level of skill in this technology. Illustrative examples of suitable salts include organic salts derived from amino acids, such as glycine and arginine, ammonia, carbonates, bicarbonates, primary, secondary, and tertiary amines, and cyclic amines, such as benzylamines, pyrrolidines, piperidine, morpholine, piperazine, N-methyl-glucamine and tromethamine and inorganic salts derived from sodium, calcium, potassium, magnesium, manganese, iron, copper, zinc, aluminum, and lithium.

The compounds of the invention, including their pharmaceutically acceptable salts, whether alone or in combination, (collectively, “active agent” or “active agents”) of the present invention are useful as MGL-modulators in the methods of the invention. Such methods for modulating MGL comprise the use of a therapeutically effective amount of at least one chemical compound of the invention.

In addition, some of the compounds of the present invention may form solvates with water (i.e., hydrates) or common organic solvents, and such solvates are also intended to be encompassed within the scope of this invention.

The term “host” refers to a mammal, in particular to humans, mice, dogs and rats.

The term “cell” refers to a cell expressing or incorporating the MGL enzyme.

The term “tissue” refers to a tissue expressing or incorporating the MGL enzyme.

Any formula given herein is also intended to represent unlabelled forms as well as isotopically labelled forms of the compounds. Isotopically labelled compounds have structures depicted by the formulas given herein except that one or more atoms are replaced by an atom having a selected atomic mass or mass number in an enriched form. Examples of isotopes that can be incorporated into compounds of the invention in a form that exceeds natural abundances include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, fluorine, chlorine, and iodine, such asH (or chemical symbol D),H (or chemical symbol T),C,C,C,N,O,O,P,P,S,F,Cl, andI, respectively. Such isotopically labelled compounds are useful in metabolic studies (preferably withC), reaction kinetic studies (with, for exampleH orH), detection or imaging techniques [such as positron emission tomography (PET) or single-photon emission computed tomography (SPECT)] including drug or substrate tissue distribution assays, or in radioactive treatment of patients. In particular, anF orC labelled compound may be particularly preferred for PET or SPECT studies. Further, substitution with heavier isotopes such as deuterium (i.e.,H, or D) may afford certain therapeutic advantages resulting from greater metabolic stability, for example increased in vivo half-life or reduced dosage requirements. Isotopically labelled compounds of this invention can generally be prepared by carrying out the procedures disclosed in the schemes or in the examples and preparations described below by substituting a readily available isotopically labelled reagent for a non-isotopically labelled reagent.